Conventional cylinder setting mechanisms for offset printing machines are so designed that the rubber blanket cylinder is brought into or out of engagement with the plate cylinder and the impression cylinder simultaneously. As a result, there can be no transfer of the plate image onto the rubber blanket cylinder before printing. In order to confirm the plate image and the suitable transfer of the plate image onto the rubber blanket cylinder and in turn onto a sheet carried on the periphery of the impression cylinder, it is necessary to use a number of sheets which are "spoiled" in the process of making the transfer and by the use of certain adjustments to finally produce a transfer image which is satisfactory. Furthermore, since the setting or releasing of the rubber blanket cylinder is carried out when the cut of the respective cylinders are not in alignment with each other, the image is not uniform in density at the start of the printing operation.
It is, therefore, an object of the present invention to provide a cylinder setting mechanism for an offset printing machine which is capable of setting the rubber blanket cylinder in contact with respect to the plate cylinder and the impression cylinder individually and in two steps and to perform the setting or releasing of the rubber blanket cylinder when the cuts of the respective cylinders are aligned with each other, permitting the plate image to be transferred onto the rubber blanket cylinder for checking prior to printing and the setting of the rubber blanket cylinder relative to the plate cylinder and the impression cylinder can be controlled separately during the printing operation eliminating the necessity to use spoil sheets and wherein the image is free from nonuniform density and wherein satisfactory prints may be obtained beginning with the first print.